caltech alumni book club


February 2018

Rise of the Rocket Girls: The Women Who Propelled Us, from Missiles to the Moon to Mars

by Nathalia Holt

Book Club Host: Sue Finley, Test Engineer at JPL, One of the original "Rocket Girls", and NASA's longest serving woman.

We take so much for granted now, but in the 1940s, 1950s, and 1960s, women who wanted a career other than homemaker were mostly limited to becoming teachers, nurses, or secretaries, and there was no such thing as maternity leave. However, a few smart young women who loved math were hired to be human computers for the Jet Propulsion Lab in California. What we think of as computers now hadn't been invented yet. These women spent their days writing equations and computing numbers with pencils, paper, and slide rules to give the male engineers the information they needed to build rockets, satellites, and space shuttles. This selection will surprise and thrill teens not only because it honors the crucial work of these female scientists but also because it shows their individual humanity—their favorite fashions, their personal relationships—within the broader context of the international space race, changes in U.S. society brought about by feminism and integration, and transformations in American daily life brought about by evolving technology.--

Meet our FEBRUARY 2018 book club host

Sue Finley, Test Engineer at NASA. She is a Rocket Girl and NASA"s longest serving woman.

Sue Finley, Test Engineer at NASA. She is a Rocket Girl and NASA"s longest serving woman.


By Erik M. Conway
From "From "
NASA's 50 Year Men and Women"

The human computer - Susan G. Finley was hired to perform trajectory computations for rocket launches by hand.

Susan G. Finley, NASA’s longest-serving woman, was hired as a “computer” by the Jet Propulsion Laboratory in January 1958, one week before JPL launched Explorer 1, America’s first satellite. Her initial job was performing trajectory computations for rocket launches by hand. She had a number of career changes at JPL as digital computers eliminated the need for hand calculations. She is now a software tester and subsystem engineer.

One of her earliest memories at JPL is of the flight of Pioneer 3, launched on Dec. 6, 1958. She was called in to calculate velocities from telemetry data when the digital computer that was supposed to do it failed. “I punched this data into the Frieden [calculator] as Al Hibbs relayed it to me from his telephone connection with the receiving antenna. I went home around 6:00 a.m. after everyone realized that it hadn’t reached escape velocity, so it wasn’t going to leave orbit. My husband was up watching the news. They had a little blackboard with the numbers on it I had calculated. I said ‘that’s my number!’”

She left JPL twice during the next few years, first to support her husband’s education, and then, after a brief period back at the lab, to have children. She returned permanently in 1969. Through most of the 1970s, she worked on a variety of advanced mission studies, calculating trajectories and orbits for a variety of potential future missions. By the end of the decade, this work, too, was being taken over by electronic computers.

In 1980, she began writing software for the Deep Space Network (DSN). The Deep Space Network, operated by JPL for NASA, tracks and receives data from all United States and many foreign interplanetary spacecraft. Finley’s major software effort was for the “Delta DOR” upgrade, which improved navigational accuracy by using quasars as fixed reference points in space. Delta DOR stands for Delta Differential One-way Range. Then she coordinated DSN support to the two joint USSR/France Vega missions to Venus and Halley’s comet. In the late 1980s, she became a task manager for another upgrade to the Deep Space Network. This improved its utility for very long baseline interferometry, a technique that links several radio antennas into a single, much more powerful one. She enjoyed this project – except for the budgeting.

In the early 1990s, Finley returned to software. She performed many tasks during the next 15 years, but one stands out in her memory – software she helped develop for the Mars Exploration Rover missions. These used a “semaphore-like” communications method during their plunge through the Mars atmosphere. The spacecraft’s transmitter sent back specific tones, or musical notes, by radio after each phase of the descent. Finley’s software received the signals from the DSN and interpreted them so the projects’ engineers would know what was going on. This task took her out to the Goldstone and Tidbinbilla stations during the landings, so she missed all the press attention the missions received.

She laughed, “They’re always focused on the control room at JPL. People really doing the work don’t get on TV.” Finley currently is involved with developing an improved version of the semaphore software for the Mars Science Laboratory mission in 2009, in addition to her subsystem and software testing duties. In her half century at JPL, she has most enjoyed “being part of exploring the universe, space, our solar system.” Finley still enjoys her work, and she has no plans to retire “unless things start to get really boring.”